Using wrapmode.once and speed cuts animation prematurely

I’m having an issue here with the animation stopping at the point defined in speed.
For example, setting the animation speed to 0.5f will make the animation play at half speed, but stop half way through the animation on a “WrapMode.Once” animation. How can I get the animation to play through entirely?

Animation[Name].speed = 0.5f;
Animation[Name].wrapMode = WrapMode.Once;
Animation.CrossFade(Name);

Try WrapMode.ClampForever